1. Field of the Invention
The present invention relates to engine analyzers, and more particularly to an engine analyzer suitable for use in determining the good or bad condition of an internal combustion engine mounted in a motor car, which includes a computer used, and which ambient electric systems including that in the engine of the motor car are automatically diagnosed, a determination of a good or bad condition as a result of the diagnosis is automatically carried out, and the results of diagnosis and the fault point or points of the aforesaid electric systems are indicated.
2. Description of the Prior Art
The characteristics of engines of motor cars and the like are determined in the course of the manufacturing process of the vehicle or during the maintenance and inspections performed on the vehicle, and proper actions are taken based on the results. In recent years, the electric systems around the engine has developed into complicated and diversified system due to the complication in functions of the motor car; and, when some of the functions are converted into electronic ones, precise measuring techniques are required from the diagnosis or measurement in the ambient electric systems including that in the engine.
Further, the characteristics of the engine and electric systems therearound are based on not a single factor but the combination of many factors complicated and correlative with one another, and hence, precise analyzing techniques and appropriate determining techniques based on the results thereof are required.
Nevertheless, heretofore, the diagnosis or measurement of the engine and the electric systems therearound have been carried out in the following manner. Namely, a skilled engineer manually evaluates the operating conditions of engine and the sounds generated by the engine, and finds a fault point or points around the engine from the abnormalities such as the vibration and sounds generated by the engine, or several measuring instruments each having a single function provided side by side, wired and connected to measuring points corresponding thereto, while an operator operates the respective measuring instruments for each measured parameters, reads the indicated values of the respective measuring instrument, and determines the measured results based on reference values which have been previously provided to the operator or remembered by the operator.
According to the conventional method as described above, it has been impossible to in detail determine the causes of abnormalities in the engine, in which the respective factors of the engine and electric systems effect, by the manual evaluation performed by the skilled operator, and particularly, it has been completely impossible to point out a fault point or points in the electric systems.
Furthermore, the provision and use of a plurality of single-function measuring instruments leads to complex wiring connections and operation of the measuring instruments, thereby considerably reducing the operation efficiency. The operator reads the values indicated by these measuring instruments and determines the measured results, whereby errors in measurement amount due to personal inability, personal error and the like, and mistakes in determining the measured results tend to frequently occur, thus making it very difficult to measure and determine correctly.
In recent years, there have been published as the means of solving these problems several measuring systems referred to as "engine analyzers" or "automatic diagnoser" for diagnosing the characteristics around the engine through the utilization of a computer. In these measuring systems, there is adopted high technology electronic techniques and computer techniques and each of the measuring systems is principally connected to predetermined points for measuring of the motor car, which includes: a plurality of detectors for detecting the characteristics of the respective measuring points as electric signals; a signal processing circuit for converting electric signals obtained from the respective detectors into signal values to be easily processed by a computer or the like; a centralized process control circuit utilizing a computer or the like provided with memory means capable of presetting reference values for determining the respective diagnosing items, successively operating and processing the outputs fed from the signal processing circuit according to a preset program, comparing the measured results for the diagnosing items with the memory values and automatically determining the results; an indicator for indicating the measured values fed from the signal processing circuit and the centralized process control circuit; and a printer for recording the measured values, determined results and the like. With these highly developed measuring systems, a plurality of complicated measuring points can be measured and diagnosed in a very short period of time, further errors in measurement made by the operator can be eliminated, the determination made by the operator's bodily senses and perception in the prior art can be completely eliminated, and uniform diagnosis can be performed without resorting to the ability of the operator. Furthermore, through the utilization of a computer, the analyzing process of complicated signals can be centrally processed very easily and with high accuracy. Thus, these highly developed measuring systems, as compared with the conventional single function measuring system, has such characteristic features as improved measuring accuracies, decreased measuring time and easier expansion of ranges of higher measurement and diagnosis. Nevertheless, heretofore, even those highly developed measuring systems have had some problems. More specifically, the conventional engine analyzer or automatic diagnoser of the type as described is not provided with a means for driving from outside the engine and electric systems associated therewith which constitute the objects of diagnosis by themselves, whereby, in order to diagnose a capacitor, an interrupter should be manually opened and suitable measuring means should be used to measure, thereby making it impossible to automatically diagnose the capacitor even with a measuring means utilizing a computer.
Furthermore, the measuring system itself cannot crank or start the engine, and hence, the operator must operate an engine key switch, thus reducing the workability. Further, the measuring system is not provided with an auxiliary electric power source means for aiding a vehicle-mounted battery of the motor car to be diagnosed, and consequently, when the vehicle-mounted battery is low in performance, sometimes it becomes very difficult to crank or start the engine. Since the conventional engine analyzer or automatic diagnoser is of the type wherein the characteristics fed from the engine are converted into electric signals to be processed, it is necessary to remove and diagnose with suitable means the elements having no signal generating function by themselves, such as a high tension cords or ignition plugs in an ignition circuit, thus making it difficult to automatically diagnose. Further, the diagnosed results in the conventional apparatus are indicated to the operator or user of the motor car to be diagnosed through the printer's record or determined result indicating lamps for the respective diagnosing items, and therefore, it takes time to read the details of the printer's record or to visually assertain diagnosis indicating lamps, and particularly, it is difficult to instruct and make understood the diagnosed results to the general users having limited knowledge about the engines. As has been described above, even if computer techniques are introduced into the engine analyzer or automatic diagnoser, heretofore, the characteristics of the engine and electric systems therearound constituting the objects to be diagnosed have not been grasped sufficiently due to the lacking functions, thus resulting in an unsatisfactory diagnoser.